<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style lang="">
        .container {
            height: 100vh;
            width: 100vw;
            text-align: center;
            box-sizing: content-box;
        }

        #ball {
            background: linear-gradient(cyan, transparent), linear-gradient(225deg, magenta, transparent), linear-gradient(45deg, yellow,
            transparent);
            width: 50px;
            height: 50px;
            border-radius: 50% 50%;
            text-align: center;
            position: absolute;
        }
    </style>
</head>

<body>
    <div class="container" id="a">
        <div style="position:absolut" id="ball">&nbsp;</div>
    </div>
    <script src="./main.js"></script>
    <script>
        window.a = document.getElementById('a')
        console.log(a.style.width)
    </script>
</body>

</html>